This project will develop a spatially explicit model using Geographic Information System (GIS) technology to predict environmental correlates of high human hantaviral risk in Chile. A combination of descriptive and analytical techniques will be used in the study both in the field and the laboratory. The major hypotheses to be tested are that; 1) surges in rodent populations can be predicted using satellite-derived climate and environmental data from a GIS, 2) fluctuations in human hantavirus infection can be predicted from fluctuations in rodent populations derived from rodent surveillance and data from hypothesis one, 3) GIS data combined with generalized models can be developed to provide techniques to predict environmental change and many human infections transmitted by animals and, 4) virus titers in blood and excretions are higher during the spring breeding pulse of reservoir rodents when young of the year are dispersing. Results from these studies will provide information on the degree of human risk associated with this virus and allow predictions regarding future outbreaks.